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RD Sharma Solutions Class 12 Mathematics Chapter 15 VSA

RD Sharma Solutions Class 12 Mathematics Chapter 15 VSA

Edited By Kuldeep Maurya | Updated on Jan 21, 2022 01:03 PM IST

Many students widely use the RD Sharma solution books to clarify their doubts without the help of a teacher or a tutor. Solving the Very Short Answers (VSA) in class 12 mathematics is trickier as the solutions must be small and solved using shortcut methods. However, students can save time and complete the sums effortlessly using this method. And to learn it, the RD Sharma Class 12th VSA book is the best choice.

RD Sharma Class 12 Solutions Chapter 15 Tangents and Normals - Other Exercise

Chapter 15 - Tangents and Normals Ex 15.1

Chapter 15 - Tangents and Normals Ex 15.2

Chapter 15 - Tangents and Normals Ex 15.3

Chapter 15 -Tangents and Normals Ex-FBQ

Chapter 15 -Tangents and Normals Ex-MCQ

Tangents and Normals Excercise:VSA

Tangents and Normals Exercise Very Short Answer Question 1

Answer :
(x1,y1)=(1,2)
Hint:
Use the slope of the tangent.
Given:
Here the curve y=x22x+3, where the tangent is parallel to xaxis.
We have to find the point on the given curve.
Solution :
The slope at the xaxis is 0.
Now,
Let (x1,y1) be the required point.
Since the point lies on the curve.
Hence y1=x122x1+3 ....(i)
Then, y=x22x+3
dydx=2x2
Slope of the tangent at (x,y)=(dydx)(x1,y1)
=2x12
Here dydx=0
2x12=0x1=1
From equation (i)
y1=12+3=2y1=2
Hence required point is (x1,y1)=(1,2)

Tangents and Normals Exercise Very Short Answer Question 2

Answer : Slope of tangent at t=2 is 67
Hint : Use equation of tangent,
yy1xx1=(dydx)(x1,y1)
Given :
Here, x=t2+3t8 and y=2t22t5
We have to find the slope of tangent to given curve at t=2
Solution :
The equation of the given curve is
x=t2+3t8....(i)y=2t22t5...(ii)
Differentiating equation (i) with respect to t
We have,
dydt=4t2dydx=dxdtdydt=4t22t+3
Now, slope of tangent at t=2
(dydx)t=2=824+3=67
Hence, Slope of tangent at t=2 is 67.

Tangents and Normals Exercise Very Short Answer Question 3

Answer : dydx=0
Hint : The curve is parallel to xaxis then slope of tangent is equal to slope of the x axis.
Given :
The tangent line at a point (x,y)on the curve y=f(x) is parallel to x axis.
We have to find the value of dydx.
Solution :
Here we have,
Slope of x axis is equal to zero.
Also, the tangent line at a point (x,y)on the curve y=f(x) is parallel to x axis.
Slope of tangent (dydx)= slope of x axis
dydx=0

Tangents and Normals Exercise Very Short Answer Question 4

Answer : dydx=0
Hint :
1. The slope of y - axis is .
2. Using, Slope of tangent=1slope of normal
Given: The normal of the curve y=f(x) at (x,y) is parallel to y -axis.
We have to write the value of dydx
Solution:
We know that,
The slope of y - axis is
Also, The normal of the curve y=f(x) at (x,y) is parallel to y - axis.
slope of normal = slope of y- axis
dydx= Slope of tangent =1 slope of normal =1=0
Hence, dydx=0

Tangents and Normals Exercise Very Short Answer Question 5

Answer : dydx=1or1
Hint:
The curve is equally inclined to the axes, then the angle made by the tangent with axes can be ±45o.
Given:
Here given that,
The tangent to a curve at a point (x,y)is equally inclined to the co-ordinate axes.
We have to write the value of dydx.
Solution :
We know that,
The tangent to a curve at a point (x,y) is equally inclined to the co-ordinate axes, the angle made by the tangent with axes can be ±45o.
dydx=slope of tangent
dydx=tan(±45o)=±1
Hence, dydx=1 or 1

Tangents and Normals Exercise Very Short Answer Question 6

Answer : dxdy=0
Hint : Slope of the y-axis is .
Given :
Given that
The tangent line at a point (x,y) on the curvey =f(x) is parallel to y-axis.
We have to write the value of dxdy.
Solution :
We know that,
The slope of the y-axis is .
Also, the tangent line at a point (x,y) on the curvey =f(x) is parallel to y-axis.
Slope of tangent=dydx = slope of y-axis
dydx=dxdy=1dydx=1=0
Hence, dxdy=0

Tangents and Normals Exercise Very Short Answer Question 7

Answer :
 slope of normal =1t2
Hint : Usingmula,
 slope of normal =1 slope of tangent 
Given :
Here given the curve,
x=1t and y=t
We have to find the slope of normal.
Solution :
Here,
x=1t and y=t
Differentiating with respect to t, we get
dxdt=1t2 and dydt=1dydx=dydtdxdt=1(1t2)
dydx=t2
So, Slope of tangent =dydx=t2
 slope of normal =1 slope of tangent 
=1t2=1t2
Hence,
 slope of normal =1t2

Tangents and Normals Exercise Very Short Answer Question 8

Answer : (x,y)=(14,12)
Hint :  slope of tangent =tanπ4=1
Given :
Here the given curve, y2=x where the tangent line makes an angle π4 with x- axis.
We have to find the co-ordinate of the point on the given curve.
Solution:
Let the required point be (x,y).
We know,
The tangent makes an angle 45owith the x-axis.
 slope of tangent =tan45=1
Since the point lies on the curve
Hence, y12=x1
Now,
y2=x
Differentiating with respect to x,
2ydydx=1dydx=12y
 slope of tangent =(dydx)(x1,y1)=12y1
12y1=1[ slope of tangent at angle π4=tanπ4=1]
2y1=1
y1=12
Now, we have,
x1=y12x1=(12)2x1=14
Hence, (x,y)=(14,12)

Tangents and Normals Exercise Very Short Answer Question 9

Answer : π2
Hint : Differentiating both equation and find dydx
Given :
Given that the curve,
x=etcost and y=etsint
We have to find the angle made by the tangent to the given curve.
Solution :
Here,
x=etcost and y=etsint
Differentiating both equation with respect to t
We have,
dxdt=etcostetsint
 - dydt=etsint+etcostdydx=dydtdxdt=etsint+etcostetcostetsint
Now, slope of tangent =(dydx)t=π4
=et(sinπ4+cosπ4)et(cosπ4sinπ4)=12+121212=220dydx=
Let θ be the angle made by the tangent with the x-axis.
tanθ=θ=π2
Hence, the angle made by the tangent to the given curve is π2.

Tangents and Normals Exercise Very Short Answer Question 10

Answer : Equation of normal =2x=π
Hint : Use equation of normal,
yy1=1dydx(xx1)
Given :
Here given that the curve
y=x+sinxcosx
We have to write the equation of normal to the given curve at x=π2
Solution:
We have,
y=x+sinxcosx
On differentiating both sides with respect to x, we get
dydx=1+cos2xsin2x
Now we know that,
 slope of tangent =(dydx)x=π2=1+cos2(π2)sin2(π2)=1+01=0
Now,
When x=π2y=π2+sinπ2cosπ2
y=π2
(x1,y1)=(π2,π2)
So, equation of normal
yy1=1 slope of tangent (xx1)yπ2=10(xπ2)
x=π22x=π
Hence the equation of the given curve at x=π2 is 2x=π.

Tangents and Normals Exercise Very short Answers Question 11

Answer : (x1,y1)=(12,1)
Hint :
For line, the slope of a line is denoted by m.
y=mx+c, where m is slope of line.
Given :
Given that the curve, y2=34x
Where the tangent parallel to the line, 2x+y2=0
We have to find the co-ordinate of the point on the given curve.
Solution :
Let (x1,y1) be the required point
We know that,
If 2x+y2=0
y=2x+2
Comparing with equation:
y=mx+c
We get, m=2
Slope of the given line =2
Since, the point lies on the curve
So y12=34x1 ...(i)
Now, y2=34x
Differentiate with respect to x
2ydydx=4dydx=2y
Slope of tangent =(dydx)(x1,y1)=2y1
Here, slope of tangent=slope of the line
2y1=2y1=1
From equation (i), we get
1=34x14x1=2x1=12
Hence, (x1,y1)=(12,1)




Tangents and Normals Exercise Very short Answers Question 12

Answer : Equation of tangent, x+y=2
Hint: Use the equation of tangent,
yy1=dydx(xx1)
Given : Here the curve,
y=x2x+2 at the point where it crosses the y-axis.
We have to write the equation of the tangent.
Solution :
We know that,
When the curve passes through y - axis, then the point on the curve is of them (0,y)
Now, y=x2x+2
Differentiating with respect to x,

dydx=2x1
Slope of tangent =(dydx)(0,2)=2(0)1
=1=m(say)
(x1,y1)=(0,2)and m=1
Equation of tangent,
yy1=m(xx1)y2=1(x0)x+y=2
Hence the required equation of tangent, x+y=2.



Tangents and Normals Exercise Very short Answers Question 13

Answer : Angle = 0o
Hint : First, find the slope of given curves then use themula:
tanθ=|m1m21+m1m2|
Given :
Given curve,
y2=4xand x2=2y3
We have to find the angle between the given curves.
Solution :
Given :
y2=4x ...(i)
x2=2y3 ...(ii)
On differentiating equation (i) with respect to x, we get
2ydydx=4
dydx=2y
m1=(dydx)(1,2)=22m1=1
Now, differentiating equation (ii) with respect to x, we get
2x=2dydx
dydx=x
m2=(dydx)(1,2)=1
m2=1
As we know that,
tanθ=|m1m21+m1m2|tanθ=|111+1|tanθ=0θ=0
Hence the required angle between the curve is 0o

Tangents and Normals Exercise Very short Answers Question 14

Answer : Required angle =π2
Hint :
  1. If m1=m2, they are parallel.
  2. If m1m2=1, they are perpendicular to each other.
Given :
Given that the curve,
y=ex and y=ex
We have to find the angle between the given curves at the point of intersection.
Solution :
Given,
y=ex ....(i)
y=ex .....(ii)
From (i) and (ii), we get
ex=exx=0
Substituting the value of x in equation (ii), we get
y=1
So, the point of intersection of the two curves is (0,1)
On differentiating (i) with respect to x, we get
dydx=exm2=(dydx)(0,1)=1
m1m2=1 Since m1m2=1,
Hence, they are perpendicular to each other.
Hence, the required angle =π2

Tangents and Normals Exercise Very short Answers Question 15

Answer : Slope of normal = 9
Hint :
 slope of normal =1 slope of  tan gent  i.e., 1dydx
Given :
Given curve,
y=1x
We have to write the slope of normal to the given curve at point (3,13)
Solution :
Here,
y=1x
On differentiating with respect to x, we get
dydx=1x2
Now,
 slope of  tan gent =(dydx)(3,13)=19 slope of normal =1 slope of tan gent 
=1(19)=9
Hence, the Slope of normal = 9

Tangent and Normals Exercise Very short Answers Question 17

Answer:

Hint :
 slope of normal =1 slope of  tangent  i.e., 1dydx
Given :
Given curve,
y=cosx    at (0,1)
We have to write the slope of normal to the given curve at point (0,1)
Solution :
Here,
y=cosx    at (0,1)
On differentiating with respect to x, we get
dydx=sinx
Now,
 slope of  tangent =(dydx)(0,1)=0 slope of normal =1 slope of tangent 
=10=
Hence, normal line is x=0.

Tangent and Normals Exercise Very short Answers Question 18

Answer:

Answer : y=x is required equation of tangent
Hint :
 Equation of tangent =(yy1)=dydx(xx1)
Given :
Given curve,
y=sinx
We have to write the equation of tangent drawn to the given curve at point (0,0).
Solution:
y=sinx
Differentiating both sides with respect to x, we get
dydx=cosx(dydx)(0,0)=cos0=1
Hence the equation of tangent at (0,0),
(y0)=1(x0)y=x
Hence, y=x is the required equation.

Tangent and Normals Exercise Very short Answers Question 18

Answer:

Answer : y=x is required equation of tangent
Hint :
 Equation of tangent =(yy1)=dydx(xx1)
Given :
Given curve,
y=sinx
We have to write the equation of tangent drawn to the given curve at point (0,0).
Solution:
y=sinx
Differentiating both sides with respect to x, we get
dydx=cosx(dydx)(0,0)=cos0=1
Hence the equation of tangent at (0,0),
(y0)=1(x0)y=x
Hence, y=x is the required equation.

Tangent and Normals Exercise Very short Answers Question 19

Answer : 0
Hint :
Simply we will find dydx at x=π6
Given:
Given curve,
y=2sin23x
We have to find the slope of the tangent to the given curve at x=π6
Solution :
y=2sin23x
Differentiating both sides with respect to x, we get
dydx=2×2sin(3x)×cos(3x)×3(dydx)x=π6=12×sin(π2)×cos(π2)
=12×1×0
(dydx)=0
Hence the slope of tangent = 0


Chapter 15 in mathematics, Tangents, and Normals consists of three exercises, ex 15.1, ex 15.2, and ex 15.3. Class 12 RD Sharma Chapter 15 VSA Solution includes concepts like finding the point of the curve, finding the slope of the tangent, slope of normal at a point, equation of the normal, coordinates of the point, and angles between the curve. RD Sharma Class 12 Solutions Tangents and Normals VSA are around 19 questions given in this exercise. Students can use the RD Sharma Class 12 Chapter 15 VSA solution book for reference.

It is mainly recommended by the CBSE board schools to its students, as the RD Sharma solutions follow the NCERT syllabus. Students can work out the practice questions to understand the steps clearly. The RD Sharma Class 12th VSA book answers are given in simple, easy methods to solve the Very Short Answers quickly. It helps the student use minimal time to solve this section during examinations.

If you are wasting time working out VSA solutions in an elaborated manner, use the Class 12 RD Sharma Chapter 15 VSA to understand how easily sums can be solved. With good practice, you'll be able to solve the Very Short Answers of the Tangents and Normals chapter in a short period. This helps you save time that can be spent rechecking the answer sheet.

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Frequently Asked Questions (FAQs)

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The students can avail the benefits of the RD Sharma Class 12th VSA solution book by clarifying their doubts regarding the very short answers given in mathematics chapter 15.

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The shortcut methods and tricks to solve the VSAs in chapter 15 are given in the RD Sharma Class 12th VSA solution book. With the help of it, you can solve the sums quickly.

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